Transfluxor magnetic switch



A ril 2, 1%8 .w. J. MAHONEY I 3,376,427

. TRANSFLVJUXOR MAGNETIC SWITCH Filed Jan. 30, 1961 2 Sheets-Sheet 1 PULSE 03c. A T012 BLOCKED fig: 2

INVENTOR WILLIAM J MAHONE Y UMBlOCKED W ATTORNEY Aprifl 1968 w. J. MAHONEY 3,376,427

TRANSFLUXOR MAGNETIC SWITCH Filed Jan. 50, 1961 2 Sheets-Sheet UNBI. OCK/NG P LSE GENEEA T02 BLOCKING PULSE GENEZA TOR UNBLOCK/NG PULSE GENE/2.4702

' OSCILLATOR BLOCK/N6 F PULSE LOAD GENERATOR INVENTOR WILLIAM J MAHONEY ATTORNEY United States Patent 3,376,427 TRANSFLUXOR MAGNETIC SWITIIH William James Mahoney, Darien, Conn., asslgnor to American Machine & Foundry Company, a corporation of New Jersey Filed Jan. 30, 1961, Ser. No. 85,763 11 Claims. (Cl. 307-88) This invention relates to magnetic devices and more particularly to magnetic devices of the transfluxor type and methods for operating the same.

The transfluxor is a magnetic device of rather recent origin capable of accomplishing switching functions without employing moving contacts. Typically, a transfluxor includes a core of a material having a rectangular hysteresis loop, the core being provided with at least a central aperture and a coupling aperture. These apertures define at least two closed magnetic paths having portions in common. Coupling can be controlled in on-off fashion between windings, employed as primary and secondary, disposed relative to the flux path defined by the coupling aperture. An alternating current signal applied to the primary winding is coupled to the secondary winding if the common portions of the magnetic paths are saturated in the same direction with respect to the coupling aperture. If, however, the common portions are saturated in opposite directions, the alternating current signal is not coupled to the secondary winding. Thus, a transfluxor can be considered as having two conditions, namely, the unblocked condition, in which coupling exists between the windings, and the blocked condition, in which no coupling exists between the windings.

The state of saturation at the common path portions is controlled by flux in the magnetic path defined by the central aperture. The blocked condition is brought about by a large control flux which affects the state of saturation in both common portions. The unblocked condition is brought about by a subsequent control flux of a predetermined magnitude suflicient to affect one of the common portions but not sufficient to affect the other. In practice, the core is somewhat diflicult to unblock if the alternating current signal is constantly running, since the primary winding is continually creating flux, which, depending on its phase, may either aid or oppose the control flux. The result is frequent occurrence of conditions referred to as underset or overset, in which the transfluxor is neither on nor off, i.e., neither blocked nor unblocked. In actual practice, underset or overset is particularly undesirable because the coupling between the primary and secondary winding, varies considerably from one on condition to the next.

In the past, underset or overset has been eliminated or corrected by either of two methods. The first method generally requires the addition of a set winding disposed about one of the common portions. A large flux created by this winding unblocks the core and is of suflicient magnitude to override the effect of any flux produced by the primary winding. The difliculty with employing a set winding is that a large number of turns may be required for such winding and these t-urns must extend through the coupling and central apertures. The physical size of the core often makes this impractical. In the second method, the magnetic core is permitted to overset, the overset subsequently being corrected for by a flux created by a large positive portion of an asymmetric pulse applied to the primary winding. However, it is difficult to construct a signal generator capable of providing an asymmetric signal sufficiently unbalanced to allow overset to be eliminated in this manner. Furthermore, the negative portion of this asymmetric signal is often large enough to spuriously unblock the core when it should remain in the blocked condition, an occurrence which is obviously disadvantageous.

Additionally, the use of a large positive drive pulse often causes the emission or leakage of a spurious output signal when the transfluxor is in the off state, due to the imperfect rectangularity of the hysteresis loop of the transfluxor core material.

It is a general object of this invention to devise an improved magnetic device for accomplishing primary switching functions without the use of moving contacts.

Another object is to provide a magnetic device of the transfluxor type which can be unblocked without encountering the problem of overset.

In order that the manner in which these and other objects are attained, in accordance Wit-h the invention, can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a schematic diagram of a transfluxor constructed in accordance with one apparatus embodiment of the invention;

FIG. IA is a diagram illustrating the flux distribution in the core of the device of FIG. 1 in accordance with one mode of the invention;

FIGS. 2 and 3 are diagrams illustrating the blocked and unblocked conditions of a transfluxor, respectively;

FIG. 4 is a schematic diagram of a transfluxor constructed in accordance with another apparatus embodiment of the invention; and

FIG. 5 is a schematic diagram illustrating a modified form of the embodiment of FIG. 4.

In essence, overset is prevented in accordance with the present invention by creating a flux which is directed about the central aperture and is in addition to the control flux. The additional flux employed in accordance with the invention opposes, in direction and magnitude, the unwanted flux created by the primary winding and existing during the presence of the unblocking control flux, the overall flux relationship being such that the total flux available to unblock the core can be controlled precisely regardless of the phase of the signal applied to the primary winding.

An additional feature of the present invention is that apparatus according to one embodiment can be operated to correct for overset rather than to prevent overset. Such operation eliminates the necessity of controlling the magnitude of the flux employed to unblock the core. In this embodiment the additional flux is created by an additional winding placed in series with the primary winding and energized by an asymmetric signal. The windings are disposed so that two fluxes created by the primary winding and the additional winding aid one another in one of the common path portions of the core and oppose one another in the other common portion. In this manner, overset, which may have occurred previously by the large unblocking control flux, is corrected.

Before proceeding with a detailed description of the invention, the operation of a conventional transfluxor will be explained, with reference to FIGS. 2 and 3, in order to establish terminology employed hereinafter. Referring to FIG. 2, there is here illustrated a transfluxor core 1 made of a magnetic material having a substantially rectangular hysteresis loop. Thus, core 1 can be of a molded ceramic ferrite of the manganese-magnesium ferrospinel type, such ferrites being conventional and commonly used for magnetic memory cores since it has two remnant states. Core 1 can be considered as an annular body, being provided with a main aperture 2, usually called the central aperture, and has a coupling aperture 3, the two apertures defining the three distinct legs or magnetic path portions indicated at 4, 5 and 6. The cross-sectional areas of legs 5 and 6 are approximately equal and the cross-sectional area of leg 4 is equal to or greater than the sum of the cross-sectional areas of legs 5 and 6. The core body surrounding central aperture 2 provides a closed overall magnetic path which includes legs 4, and 6. Surrounding coupling aperture 3 is a closed magnetic path passing through legs 5 and 6. These two magnetic paths have two portions in common, i.e., legs 5 and 6.

A primary winding 7 and a secondary winding 8 are wound about leg 6 and pass through the coupling aperture. A control Winding 9 is wound about leg'4 and passes through the central aperture.

If a large current pulse is applied to control winding 9 with a polarity which creates a flux in leg 4 in the direction shown by the arrows, flux flows clockwise about central aperture 2 and saturates legs 5 and 6 in the downward direction, as shown in the drawing, with the result that the core is blocked. The magnetic path surrounding coupling aperture 3, shown as shaded area for convenience, cannot support a change influx and therefore primary winding 7 is not coupled to secondary winding 8. Flux cannot flow clockwise around the coupling aperture because leg 6 is already saturated in this direction. Similarly, flux cannot flow in the counterclockwise direction about the coupling aperture because leg 5 is already saturated in that direction.

The magnetic core can subsequently be unblocked by creating a flux flowing about central aperture 2 in a counterclockwise direction, as shown in FIG. 3. At the outset, the core is blocked and therefore saturated in the direction shown by the broken arrows. The magnetic field produced by a pulse applied to control winding 9 is strongest nearest the center of central aperture 2 and decreases in strength as the radial distance from the center of the aperture increases. Since core 1 is constructed of rectangular hysteresis loop material, the direction of saturation is reversed only as far as a certain critical circumference 11. In effect, the counterclockwise flux created by control winding 9 establishes two separate areas, highly saturated in opposite directions, with a sharply defined boundary of nonsaturated material located at the critical circumference. The magnetic material located within the critical circumference is saturated in the direction shown by the solid arrows. The magnetic material located outside the critical circumference remains unchanged and is therefore saturated in the direction of the broken arrows. The core is now unblocked and primary winding 7 is coupled to secondary winding 8. If current is first supplied to primary winding 7 in a direction tending to produce a clockwise flux about the coupling aperture, this flux cannot flow. If current is subsequently applied to primary winding 7 tending to produce flux in the opposite direction, this flux can flow around coupling aperture 3, and reversals in direction of the current flow thereafter applied to primary windings 7 can produce changes of flux about this aperture. Accordingly, signals applied to primary winding 7 induce potentials in secondary winding 8 and therefore the core is unblocked and the windings are effectively coupled.

If the unblocking current pulse applied to control Winding 9 is decreased, the critical circumference decreases and, if the unblocking current pulse is increased, the critical circumference increases. If the critical radius is not located such that it passes through the center of coupling aperture 3, either underset or overset occurs. Underset or overset conditions fall somewhere between the blocked condition and the unblocked condition and results in some coupling between primary winding 7 and secondary winding 8. The coupling in both cases, however, is considerably less than would exist during the fully unblocked condition. Since this is neither the on condition nor the off condition, underset and overset are to be avoided. This is sometimes diflicult to accomplish, since primary winding 7 is normally connected to a continuously operating oscillator and a flux of changing direction is continually tending to flow about coupling aperture 3. Depending on phase, this flux may either aid or oppose the unblockin flux created by the control winding, resulting in variations of the critical circumference and either underset or overset.

Overset can be prevented, in accordance with one embodiment of the present invention, in the manner illustrated schematically in FIG. 1. Here, the transfluxor ineludes a magnetic core 12 of a material having a substantially rectangular hysteresis loop, the core being provided with a central aperture 13 and a coupling aperture 14. Apertures 13 and 14 define legs 15, 16 and 17. Legs 16 and 17 are common to the magnetic path surrounding central aperture 13 and the magnetic path surrounding coupling aperture 14. A primary winding 18 and a secondary winding 19 are wound about leg 17 and pass through the coupling aperture. A winding 20 and a control winding 21 are wound about leg 15 and pass through the central aperture. Winding 20 is connected in series with primary winding 18 and is so wound that, when the primary winding is energized to produce a flux directed counterclockwise around coupling aperture 14, winding 20 produces a flux directed clockwise about central aperture 13.

Primary winding 18 is connected to a suitable signal source, such as oscillator 22, and secondary winding 19 is connected to a load 23. The waveform generated by oscillator 22 is asymmetric and should have the waveform shown in the drawing, with the large positive portion being referred to as the drive pulse and the smaller negative portion being referred to as the prime pulse. The asymmetric signal is of a polarity to primary winding 18 that the drive pulse produces a counterclockwise flux about the coupling aperture 14 and of a polarity in winding 20 to cause a clockwise pulse around the central aperture '13. The drive pulse may be large without any danger of spuriously unblocking the core, since the fluxes from the windings 18 and 2t) combine in the downward direction (the direction of block) in leg 16 but oppose one another in leg 17. Accordingly, neither leg 16 nor leg 17 can be changed from the downwardly saturated, blocked direction. The prime pulse, however, must be limited in magnitude since the pulse of this polarity could spuriously unblock the core. The fluxes produced by the prime pulse combine in the upward direction in leg 16 and could reverse the direction of saturation to the upward direction, thus unblocking the core. Accordingly, when the core is blocked, with legs 16 and 17 both saturated in the downward direction, the asymmetric signal with a large positive drive pulse and a small negative prime pulse will not unblock the core.

The presence of current in the winding 20 does not adversely affect the normal transfer of energy from primary 18 to secondary 19 after the unblocking pulse has ceased, inasmuch as the magnetomotive force generated by winding 20 is insufficient to overcome the threshold of coercivity of the path around the central aperture, thus being unable to exert influence upon fluxes in either leg 16 or 17. However, during the occurrence of theunblocking pulse which does overcome the threshold of coercivity, energy from winding 20 is enabled to exert influence in legs 15, 16 and 17 as will be later explained. The purpose of the transfluxor is to selectively establish coupling between the primary and secondary windings and thereby selectively apply a signal to the load. Since oscillator 22 is continuously operating and connected to primary winding 18, the overset problem is present.

Connected to control winding 21 is a pulse oscillator 24 capable of selectively producing pulses of either polarity in order to block or unblock the core. Assume that a pulse of a first polarity produces a large flux flowing about central aperture 13 in a clockwise direction, thus producing the blocked condition as described in connection with FIG. 2. This flux is sufficiently large to override the effect of any other flux tending toflow in the core.

To unblock the core in this embodiment, pulse oscil lator 24 is operated to produce a pulse of second polarity and of a limited magnitude. This pulse creates a flux which flows in a counterclockwise direction about central aperture 13 and it must have a minimum amplitude capable of changing the saturation direction of material out to a critical circumference which should pass slightly beyond the center of the coupling aperture 14, in eifect slightly oversetting the core. If the unblocking pulse coincides with the prime phase of the oscillator 24 tending to flow about the coupling aperture 14 in the clockwise direction, the magnetomotive forces provided by the oscillator signal in both windings 18 and 20 tend to counteract each other in leg '17 and prevent the undesired interaction with the unblocking pulse. The fluxes from windings 18 and 20 add in leg 16 and are in the same upwardly direction as the flux provided by the control pulse in winding 21. This leg 16 is therefore fully saturated. If the unblocking pulse, however, coincides with drive phase of the oscillator 22 tending to flow about the coupling aperture in the counterclockwise direction, the magnetomotive force from windings 18 and 2t combine in the downward direction in leg 16 and are of sufiicient total magnitude to prevent the counterclockwise unblocking pulse from exerting any influence in leg 16. The force lines from said unblocking pulse therefore will be forced to depart from the usual doughnut shape encompassing leg 16 and be diverted all into leg 17 in an upward direction, reversing substantially all the magnetic material in leg 17. The two fluxes from this drive phase of the oscillator signal cancel each other in leg 17 so no opposition is oifered to the above mentioned fiux from winding 21 flowing in leg 17 at this time. Upon the cessation of the control pulse the core is then left in the condition of leg 16 being saturated in the downward direction and leg 17 saturated in the upward direction, the condition necessary for maximum coupling of primary winding 18 and secondary winding. 19.

The fluxes which are present when the flux created by the unblocking pulse coincides with the fluxes from the negative prime phase from oscillator 22 are shown in FIG. 1A. Flux a is a counterclockwise flux about the central aperture 13 as produced by the control winding 21. The magnitude of this pulse alone is sufiicient to saturate all the material in leg 16 in the upward direction. Flux b is the clockwise flux about the coupling aperture 14 produced by the primary winding 18. Flux c is a counterclockwise fluX provided by control winding 21 which is in excess of that needed to fully saturate leg 16 and reverses some magnetic material in leg 17. Fluxes d and e are produced by additional winding 20 in a counterclockwise direction about the central aperture. Since additional winding 20 is in series with the primary winding 18, the flux produced by winding 20 is always proportional to the flux produced by the primary winding. Accordingly, flux e is always in the correct direction and magnitude to cancel the eifect of flux b, thus eliminating the unwanted effect of flux b upon flux c, contributed by the. control pulse. In this mode of operation it is necessary to limit the amplitude and duration of the control pulse.

The necessity of limiting the pulse supplied to control winding 21, when unblocking the core, can be eliminated in a second mode of operation. This mode of operation for the transfluxor shown in FIG. 1 employs arbitrarily large pulses applied to control winding 21. A large pulse, which produces a flux in the clockwise direction about the central aperture saturates legs 16 and 17 in the downward direction and blocks the core. The asymmetric signal applied to primary winding 18 and winding 20 is inoperative to unblock the core under these conditions. The core could be conditioned for unblocking, however, by applying an arbitrarily large pulse to control winding 21 which would produce a large counterclockwise flux about the central aperture, saturating legs 16 and 17 in the upward direction. This is also a blocked condition, in the reverse direction. However, the first subsequent drive pulse applied to primary winding 18 and winding 20 combines in leg 16 in a downward direction and is capable of changing the direction of saturation of all the magnetic material in leg 16, thereby unblocking the core.

This mode of operation differs from the prior art mentioned earlier wherein the transfluxor is purposely overset and the overset subsequently being corrected for by a flux created by a large drive portion of an asymmetric pulse applied to the primary winding alone. In the earlier art described in the paper The Transfiuxor by Rajchman and Lo, Proceedings of the IRE, March 1956, there is no Winding 20 and the oscillator signal is so phased that the large drive pulse is in the clockwise direction around the coupling aperture 14, being in the downward direction in leg 17. The drive pulse must be of a considerably larger magnitude than in the embodiment of this invention because it must overcome the coercivity of the long outside circumference path of the core in order to effect an exchange of flux from leg 17 into leg 15, thus positioning the flux in leg 15 in a downward direction. As leg 16 remains in the upward direction the flux around the coupling aperture 14 is then in condition to transfer energy between the primary winding 18 and load winding 19. In the blocked condition the large drive pulse required for such operation can cause undesirable leakage currents to be coupled into the secondary winding as some coupling always exists between primary and secondary due to the imperfect squareness of the hysteresis loop when saturated. The addition of winding 20 and the reversal of oscillator 22 polarity as described in this invention enables the drive signal to reverse the overset flux in leg 16, using the short path existing around the periphery of the large aperture 16. Said shorter path, with its lower coercivity threshold, allows a much smaller magnetomotive force for the flux reversal of leg 16 and this need be supplied only in part by winding 18, the remainder being contributed by winding 20.

Therefore the amplitude of the drive phase is allowed to be considerably smaller in winding 18, avoiding the aforementioned leakage problem in the secondary winding 19, thus improving the operation of the entire system.

A second embodiment according to the present invention is shown in FIG. 4 and includes a magnetic core 26 of magnetic material having a substantially rectangular hysteresis loop, the core being provided with a central aperture 27 and a coupling aperture 28. These apertures define legs 29, 30 and 31. The core thus provides a first magnetic path around central aperture 27, passing through legs 29, 30 and 31, and a second magnetic path around coupling aperture 28, passing through legs 30 and 31. Legs 30 and 31 are common to both magnetic paths. A primary winding 32 and a secondary winding 33 are wound around leg 31 and pass through the coupling aperture. A blocking winding 35 and an unblocking winding 34 are Wound around leg 29 and pass through the central aperture.

Asymmetric signals generated by oscillator 36 are of a polarity so applied to primary winding 32 that the drive pulse produces a clockwise flux about the coupling aperture and the prime pulse produces a counterclockwise flux about the coupling aperture. An asymetric pulse is employed in this embodiment since it permits the largest possible transfer of energy to the secondary winding 33. In this instance, the limiting feature is the tendency for counterclockwise flux to flow about the coupling aperture. If this fiux is suificiently large, it can flow around the central aperture and through leg 29, so spuriously unblocking the core. Secondary winding 33 is connected to a suitable load device 37. The purpose of the transfluxor is to selectively couple energy between primary winding 32 and secondary winding 33.

Blocking winding 35 is connected to a source of blocking pulses such as may be provided by pulse generator 38. The pulse from this generator, of the polarity shown Z on the leads of blocking winding 35, is sufficiently large to produce a fiux which flows clockwise about central aperture 27', bringing about the blocked condition. This flux is sufliciently large to override flux produced by any of the other windings. Unblocking winding 34- is connected to a source of unblocking pulses which are produced by a suitable pulse generator 39. The pulses applied to unblocking Winding 34. are of the polarity shown in FIG. 4 and are of sufficient magnitude to change the state of saturation of material as far out from the center of the central aperture as a critical circumference passing through the center of the coupling. aperture. Unblocking winding 34 is also connected to oscillator 36 via coupling resistor 40. In addition to the flux produced by the unblocking pulse, a second superposed flux is produced by energy coupled through resistor 40. This second flux is of such magnitude and direction as to at least substantially cancel flux which would otherwise be directed about central aperture 27 by the primary winding. Thus, the unwanted effect of oscillator pulses applied to the primary winding during the time of the unblocking pulse is substantially eliminated. Energy coupled to unblocking winding 34 through coupling resistor 40, in the absence of an unblocking pulse, has no effect on the core, since the flux produced thereby is insulficient to overcome the coercivity threshold of the magnetic path around the central aperture.

A third embodiment according to the present invention is shown in FIG. 5 and is similar in all respects to that shown in FIG. 4 except that resistor 40 is eliminated and capacitor 41 is used in its place. The use of the capacitor is often advantageous, since it removes the direct current component from the asymmetric signal, thus permitting a drive pulse and a prime pulse of approximately equal magnitude to be applied to unblocking winding 34. In effect, this increases the size of the prime pulse applied to the unblocking' windingv 34; which is desirable, since the prime pulse: applied to primary winding 32 during the presence of the unblocking pulse is in the counterclockwise direction and is the one which combines with the counterclockwise unblocking flux.

While particularly advantageous embodiments of the invention have been chosen for illustration, various changes and modifications can be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is':

1'. In a magnetic device, the combination of a core of magnetic material, said core having a plurality of apertures defining a first and a second magnetic path having common portions; a primary winding adapted to be energized from a source of asymmetric oscillator pulses; a secondary winding, said primary winding and said secondary winding being operatively disposed relative to said core'to be magnetically coupled by fiux'in said second magnetic path; a set winding and a block winding separately disposed relative to said first magnetic path and operative to control the remnant state of said second magnetic path; and impedance means coupled between said primary winding and said set winding operative to control the magnitude of the flux created by said set winding in accordance with the magnitude of the signal energizing said primary winding.

2. A device in accordance with claim 1 wherein said impedance means is a resistor.

3. A device in accordance with claim 1 wherein said impedance means is a capacitor.

4. In a magnetic device operative as a switch, the combination of a saturable magnetic core having a plurality of apertures therein defining at least first and second magnetic paths having portions in common; first control means operatively coupled to said. first magnetic path for providing selectively therein either a first magnetic flux in one direction to saturate said common portions in one sense and so block the core and prevent any substantial flow of magnetic flux in said second magnetic path, or a second magnetic flux in the opposite direction to saturate said common portions in the opposite sense and so condition the core; and second control means physically coupled to the uncommon portion of said first and second magnetic paths for providing fluxes therein to change the saturated state of only one of said common portions when said core is conditioned, thereby unblockidng said core and permitting the flow of magnetic flux in said second magnetic path.

5. In a magnetic device operative as a switch, the combination of a saturable magnetic core having 'a plurality of apertures therein defining at least first and second magnetic paths having portions in common; first control means operatively coupled to said first magnetic path for providing selectively therein either a first magnetic flux in one direction to saturate said common portions in one sense and so block the core and prevent any substantial flow of magnetic flux in said second magnetic path, or a second magnetic flux in the opposite direction to saturate said common portions in the opposite sense and so condition the core; and second control means operatively coupled to said first and second magnetic path for providing fluxes therein to change the saturated state of only one of said common portions when said core is conditioned, thereby unblocking said core and permitting the flow of magnetic flux in said second magnetic path, said. second control means comprising a source of asymmetric electrical signals, and a first and second winding connected to said source in series, said first and second windings being operatively coupled to said first and second magnetic paths, respectively.

6. In a magnetic device, the combination of a magnetic core having at least a central and coupling aperture therein defining respectively a first and a second magnetic path with portions in common; a control means including a control winding, operatively coupled to said first magnetic path via said central aperture for selectively saturating the common portions in accordance with the polarity of electrical energy applied to said control winding; a primary winding and a secondary winding coupled to said second magnetic path via said coupling aperture, the coupling between said primary and' secondary windings being determined by the saturated state of said common portions; an auxiliary winding coupled to said first magnetic path via said central aperture; and a source of asymmetric electrical signals which contain alternately a large positive drive pulse and a small negative prime pulse, said source being connected to energize said primary winding and said auxiliary winding.

7. In a magnetic switching device, the combination of a magnetic core having at least two apertures therein defining a first and second magnetic path with portions in common; a primary winding and a secondary winding each operatively coupled to said second magnetic path; an auxiliary winding operatively coupled to said first magnetic path; a source of asymmetric oscillator signals consisting of alternate large drive pulses and small negative prime pulses, said source being connected to energize said primary winding and said auxiliary winding; and control means operatively coupled to said first magnetic path for selectively providing therein a first magnetic flux in one direction, to block said core and eliminate any substantial coupling between said primary and secondary windings, a second magnetic flux in the opposite direction to bring about the unblocked state in said core and couple said primary winding to said secondary winding.

8. A magnetic switching device in accordance with claim 7 wherein said second magnetic flux is of a predetermined quantity, and flux from said auxiliary winding eliminates the effect of flux from said primary winding in said common portions.

9. A magneto switching device in accordance with claim 7 wherein said second magnetic flux is arbitrarily large and operative to condition the core for blocking, and the fluxes provided by said auxiliary winding and said primary winding aid in one of said common portions to unblock said core when said core is conditioned.

10. In a magnetic device, the combination of a magnetic core having at least two apertures therein defining first and second magnetic paths having portions in common, said core being blocked when said common portions are saturated in different directions with respect to said second magnetic path and unblocked when said common portions are saturated in the same direction; first control means operatively coupled to said first magnetic path to selectively provide therein a magnetic flux in one direction to block said core, and a magnetic flux in the opposite direction to condition said core for unblocking; and second control means operatively coupled to both of said magnetic paths to provide therein simultaneously magnetic fluxes which aid one another in one of said common portions, whereby a substantial net flux in one direction only results in said one common portion to preclude persist.- ence of said conditioned state.

11. A magnetic switching device comprising in combination, a saturable magnetic core having at least a control aperture and a coupling aperture therein defining a first and a second magnetic path with portions in common; control means including a control winding, operatively coupled to said first magnetic path via said central aperture for selectively saturating the common magnetic path portions in accordance with the polarity of the electrical energy supplied by said control means through its control winding; a primary and a secondary winding coupled to References Cited UNITED STATES PATENTS 3,212,067 10/1965 Rajchman et al 340-174 3,323,113 5/1967 Bennion 340174 2,993,197 7/1961 Broadbent 340174 2,994,069 7/1961 Rajchman et al 340174 3,117,308 l/1964 Sublette 340-174 3,144,639 8/1964 Richard et al. 340174 3,197,745 7/ 1965 Sweeney 340-174 OTHER REFERENCES Proceedings of the IRE, pp. 321-332, March 1956, No. 57.

BERNARD KONICK, Primary Examiner. L. SRAGOW, Examiner. S. URYNOWICZ, Assistant Examiner. 

1. IN A MAGNETIC DEVICE, THE COMBINATION OF A CORE OF MAGNETIC MATERIAL, SAID CORE HAVING A PLURALITY OF APERTURES DEFINING A FIRST AND A SECOND MAGNETIC PATH HAVING COMMON PORTIONS; A PRIMARY WINDING ADAPTED TO BE ENERGIZED FROM A SOURCE OF ASYMMETRIC OSCILLATOR PULSES; A SECONDARY WINDING, SAID PRIMARY WINDING AND SAID SECONDARY WINDING BEING OPERATIVELY DISPOSED RELATIVE TO SAID CORE TO BE MAGNETICALLY COUPLED BY FLUX IN SAID SECOND MAGNETIC PATH; A SET WINDING AND A BLOCK WINDING SEPARATELY DISPOSED RELATIVE TO SAID FIRST MAGNETIC PATH AND OPERATIVE TO CONTROL THE REMNANT STATE OF SAID SECOND MAGNETIC PATH; AND IMPEDANCE MEANS COUPLED BETWEEN SAID PRIMARY WINDING AND SAID SET WINDING OPERATIVE TO CONTROL THE MAGNITUDE OF THE FLUX CREATED BY SAID SET WINDING IN ACCORDANCE WITH THE MAGNITUDE OF THE SIGNAL ENERGIZING SAID PRIMARY WINDING. 